I have visited Makuhari Messe on countless occasions, and have always found the events to be well organised, catering to English speakers, and generally quite entertaining shows and exhibitions. The only downside of Makuhari Messe is the location. It takes a long time by train, and is a good ten minute walk from the train station at a brisk pace. Luckily, the venue often provide free and regular shuttle bus service when an event is taking place, so you can at least shave ten minutes off the otherwise long travel time from Tokyo.